Mossbauer spectroscopy methods are discussed when applied to test the properties of magnetic suppositories used in medicine. The experiments were carried out on magnetic rectal suppositories containing parmadine and fine-dispersed ferrite powder (BaOㆍnFe$_2$O$_3$) as a magnetic filler. According to the data on the value of effective magnetic field on $^{57}$ Fe nuclei in ferrite magnetic sublattices, the stoichiometric n-number equals approximately 5.5; this value corresponds to the composition range of optimal magnetic properties.